Conventional turbochargers are driven by waste exhaust heat and gases, which are forced through an exhaust turbine housing onto a turbine wheel. The turbine wheel is connected by a common turbo-shaft to a compressor wheel. As the exhaust gases hit the turbine wheel, both wheel simultaneously rotate. Rotation of the compressor wheel draws air in through a compressor housing, which forces compressed air into the engine cylinder to achieve improved engine performance and fuel efficiency. Turbochargers for variable speed/load applications are typically sized for maximum efficiency at torque peak speed in order to develop sufficient boost to reach peak torque. However, at lower speeds, the turbocharger produces inadequate boost for proper engine transient response.
To overcome these problems and provide a system that increases efficiency, a super-turbocharger can be used, which combines the features of a supercharger and a turbocharger. Super-turbochargers merge the benefits of a supercharger, which is primarily good for high torque at low speed, and a turbocharger, which is usually only good for high horsepower at high speeds. A super-turbocharger combines a turbocharger with a transmission that can put engine torque onto the turbo shaft for supercharging and elimination of turbo lag. Once the exhaust energy begins to provide more work than it takes to drive the compressor, the super-turbocharger recovers the excess energy by applying the additional power to the piston engine, usually through the crankshaft. As a result, the super-turbocharger provides both the benefits of low speed with high torque and the added value of high speed with high horsepower all from one system.